JP7061603B2 - Multi-layer hard film coating cutting tool - Google Patents

Description

The present invention relates to a multi-layer hard film coated cutting tool (hereinafter, also simply referred to as "coated tool") used for cutting metal materials, etc., and in particular, for normal (low speed) cutting and high speed cutting of carbon steel, alloy steel, etc. The present invention relates to a multi-layer hard film-coated cutting tool that exhibits a long life in both cases.

Generally, covering tools are used for turning and planing of various types of steel and cast iron, such as inserts that can be detachably attached to the tip of a cutting tool, and drilling and cutting of work materials. There are drills and miniature drills, as well as solid type end mills used for surface drilling, grooving, shoulder machining, etc. of work materials, and inserts can be attached and detached to perform cutting in the same way as solid type end mills. Insert type end mill tools and the like are known.

In recent years, there is a high demand for higher efficiency in the cutting of metal materials, and it is required to increase the cutting speed. Therefore, it is required to improve the wear resistance and the fracture resistance of the coating film covering the surface of the tool substrate of the cutting tool.

For example, in Patent Document 1, the first to third hard coatings made of TiAlCrSiN and the second hard coating made of TiSiN are covered in a covering tool such as a drill. The hard film is coated in the order of the first hard film, the second hard film, and the third hard film from the base material side of the covering tool, and the film thickness of the first hard film is Covering tools such as drills that are thicker than the thickness of the second and third hard films have been proposed, and by adopting such a hard film coating structure, the film of each hard film forming a multilayer film is formed. Since the stress is reduced, it is said that even a small-diameter cutting tool such as a drill can coat the multilayer film and exhibit excellent wear resistance.

Patent Document 2 describes the strength of the (111) plane in X-ray diffraction in a coating tool in which at least two layers of a layer made of Ti nitride or carbonitride and a layer made of TiAl nitride or carbonitride are coated. Is I (111), and when the strength of the (200) plane is I (200), the value of I (200) / I (111) of the nitride or carbonitride layer of Ti is 1 or less, and Ti, The value of I (200) / I (111) of the nitride or carbonitride layer of Al is 1 or more, and Ti nitride is in the middle of each layer to be coated in multiple layers, and the nitride layer and Ti, Al nitride are in the middle. , A covering tool in which an intermediate layer having a thickness of 5 nm to 500 nm composed of both carbonitride layers is interposed has been proposed, and such a layer structure (that is, Ti nitrides having different orientations, carbonitrides and TiAl) has been proposed. By coating two types of films, nitride and carbonitride, in multiple layers), the residual compressive stress of the layer is reduced, which makes it possible to make the film thicker, and as a result, it is said that wear resistance is improved. ing.

Further, in Patent Document 3, a total of four or more layers of a first composite nitride layer and a second composite nitride layer are alternately formed as a hard coating layer on the surface of a tool substrate made of a tungsten carbide-based cemented carbide. The first composite nitride layer formed is formed directly on the surface of at least the tool substrate, has an average layer thickness of 0.5 to 1.25 μm, and has a composition formula: (Al _1-X Ti _X ). ) A composite nitride layer of Al and Ti having an average composition satisfying 0.3 ≤ X ≤ 0.7 (where the X value is an atomic ratio) when represented by N, and the second composite nitride. The material layer has an average layer thickness of 0.5 to 1.25 μm, and when expressed by the composition formula: (Al _1-a Cr _a ) N, 0.2 ≦ a ≦ 0.6 (where a). A covering tool (drill) having an average composition of Al and Cr composite nitride layer satisfying the atomic ratio) has been proposed. According to this covering tool (drill), it is hard in cutting carbon steel. It is said that the tool life can be extended because the wear and peeling of the coating layer can be suppressed.

Further, in Patent Document 4, as a cutting tool, at least one (Al _y Cr _1-y ) X layer (however, 0.2 ≦ y ≦ 0.7, and X is N, C, B. , CN, BN, CBN, NO, CO, BO, CNO, BNO, one element of CBNO) and one (Tiz Si _{1-z )} X layer (where 0.99 ≧ z ≧) At least one layer selected from the group consisting of 0.7) is provided as a hard material layer.
The hard material layer is further mixed with one (AlCrTiSi) X mixed layer, one (Ti _z Si _1-z ) N layer or (Al _y Cr _1-y ) N layer, and then one (AlCrTiSi) X mixed layer. With at least one layer package, with the configuration of a layer followed by one (Al _y Cr _1-y ) N layer.
One layer thickness of the (Al _y Cr _1-y ) N layer or a plurality of (Al _y Cr _1-y ) N layers of the layer package is 75 nm to 200 nm, or the (Ti _z Si _1- ) of the layer package. _z ) The N layer has a layer thickness of 50 to 150 nm, and the (AlCrTiSi) X mixed layer of the layer package has a layer thickness of 20 ± 10 nm, and has an improved wear resistance having a multi-layered hard material layer. Covering tools have been proposed.
Further, the patent document 4 describes the at least one (Al _y Cr _1-y ) X layer, one or more (Al _y Cr _1-y ) N layers of the layer package, and the (AlCrTiSi). The X mixed layer can further comprise at least one of W, V, Mo, Nb and Si (see paragraph 0017), and the hard material layer is provided with a layer package of 4 to 11 (claims). 5) Further, one (Al _y Cr _1-y ) X surface layer or one (Tiz Si _{1-z )} X surface layer is formed on the outermost surface of the hard material layer (claim 8). See) is described.

Japanese Unexamined Patent Publication No. 2014-69258 Japanese Patent No. 3705381 Japanese Unexamined Patent Publication No. 2014-87858 Japanese Patent No. 5289042

In recent years, the automation of cutting equipment has been remarkable, while there are strong demands for labor saving, energy saving, and cost reduction for cutting, and versatility that can be used under both normal (low speed) cutting and high speed cutting conditions. There is a demand for cutting tools.
For example, the covering tool proposed in Patent Document 2 shows excellent tool life without occurrence of defects in cutting in a high-speed region, but chipping occurs in cutting in a normal (low-speed) region. There is a problem that the tool life is reached in a short period of time due to the above.
On the other hand, the covering tool proposed in Patent Document 3 shows excellent tool life with little occurrence of chipping in normal (low speed) region cutting, but in high speed region cutting. There is a problem that the tool life is reached in a short period of time due to the occurrence of defects.
Further, in the covering tools proposed in Patent Documents 1 and 4, when the tool life is to be extended by thickening the outermost surface layer of the multi-layered coating, the internal stress in the layer increases, and cutting is very difficult. Since the cutting edge is likely to be chipped due to the load during processing, there is a problem that not only the life extension effect commensurate with the layer thickness cannot be obtained but also the processing quality is deteriorated.
As described above, a versatile covering tool that exhibits excellent wear resistance without the occurrence of abnormal damage such as chipping and chipping under both normal (low speed) cutting conditions and high speed cutting conditions is desired. There is a demand for a covering tool that can extend the life of the tool by thickening the hard film.

Therefore, from the above-mentioned viewpoints, the present inventors exhibit performance having versatility under both normal (low speed) cutting conditions and high speed cutting conditions, and cause abnormal damage such as chipping and chipping. We conducted intensive research to develop a covering tool with a long tool life that exhibits excellent wear resistance over long-term use.

The present inventors, in particular, conducted research on the layer structure of the covering tool, and obtained the following findings.
(1) In a coated tool in which the surface of a tool substrate made of a WC-based cemented carbide or the like is coated with a multilayer hard coating, the upper layer of the multilayer rigid coating is composed of (Tiz Si _{1-z )} X, and the coating tool is formed. Optimize the layer thickness of the upper layer,
(2) A lower layer made of a multi-layered film is formed between the upper layer and the tool substrate, and the multi-layered film is also referred to as a (Al _y Cr _1-y ) X layer (hereinafter, also referred to as "A layer"). ) And the mixed layer of the (Ti _z Si _1-z ) X and the (Al _y Cr _1-y ) X (hereinafter, also referred to as “B layer” or (AlCrTiSi) X mixed layer). Formed as
(3) When the layer thickness of the A layer and the layer thickness of the B layer are optimized and the combination of one A layer and one B layer is paired, the lower layer is in the range of 2 pairs to 8 pairs. By constructing it with the repeating logarithm of the inside, the number of different interfaces leading to an excessive increase in stress is appropriately reduced, and the volume fraction of the B layer is increased in order to relax the stress.
The covering tool of the present invention coated with a multilayer hard film satisfying the conditions specified in (1) to (3) above has abnormal damage such as chipping and chipping under both normal (low speed) cutting conditions and high speed cutting conditions. It exhibits excellent wear resistance without causing any damage, and there is no risk of abnormal damage such as chipping and chipping even if the upper layer is thickened. They found that they would demonstrate their performance.
Further, in addition to the above (1) to (3),
(4) In the B layer, when a periodic composition change is formed in the layer with a predetermined periodic length and a predetermined composition volatility for other component elements other than the component X, only the stress relaxation effect of the B layer is obtained. Instead, it has been found that the effect of improving the wear resistance is obtained, so that the chipping resistance, the chipping resistance, and the wear resistance are further improved, and the life of the coated tool can be extended.

The present invention has been made based on the above findings.
"(1) In a multi-layer hard film-coated cutting tool including the tool substrate in which a multi-layer hard film is formed on the surface of the tool substrate.
(A) The multilayer hard film includes at least an upper layer as the outermost layer of the multilayer hard film and a lower layer provided between the outermost layer of the multilayer hard film and the surface of the tool substrate .
(B) The upper layer as the outermost layer of the multilayer hard film is composed of a compound layer of Ti, Si and X having a layer thickness of 0.075 to 1.5 μm containing Ti and Si, and the Ti, A compound of Si and X,
Composition formula: (Tiz Si _{1-z )} X
When represented by, 0.7 ≦ z ≦ 0.99 (where z is an atomic ratio) is satisfied, and X is N, C, B, CN, BN, CBN, NO, CO, BO, CNO. , BNO, CBNO, which is one of the following
(C) The lower layer is composed of a multi-layered film of A layer and B layer, and the layer thickness of the B layer is the same as or thicker than the layer thickness of the A layer, and the ratio of the thickness is A. Layer: B layer = 1: 1 to 1: 2, and when the combination of one A layer and one B layer is a pair, many having a repeating logarithm in the range of 2 pairs to 8 pairs. Consisting of laminated film
(D) The layer A is a compound layer of Al, Cr and X containing at least Al and Cr, and the compound of Al, Cr and X is used.
Composition formula: (Al _y Cr _1-y ) X
When represented by, 0.2 ≦ y ≦ 0.7 (where y is an atomic ratio) is satisfied, and X is N, C, B, CN, BN, CBN, NO, CO, BO, CNO. , BNO, CBNO, which is one of the following
(E) The B layer is a mixed layer of the (Ti _z Si _1-z ) X and the (Al _y Cr _1-y ) X, and the X is N, C, B, CN, BN, CBN. , NO, CO, BO, CNO, BNO, CBNO, a multi-layer hard film coating cutting tool.
(2) The mixed layer is composed of a (Ti _z Si _1-z ) X layer and a (Al _y Cr _1-y ) X layer, and the composition of the mixed layer is an individual (Ti _z Si _1-z ) X. It is an alternating stack of layers and individual (Al _y Cr _1-y ) X layers, and the individual (Tiz Si _{1-z )} X layers and individual (Al _y ) X layers constituting the mixed layer. The multilayer hard film-coated cutting tool according to (1), wherein each of the Cr _1-y ) X layers does not exceed 100 nm.
(3) The multilayer hard film-coated cutting tool according to (1) or (2), wherein the upper layer containing at least Ti and Si has a layer thickness of 0.2 to 1.5 μm.
(4) The multilayer hard film-coated cutting tool according to (1) or (2), wherein the upper layer containing at least Ti and Si has a layer thickness of 0.6 to 1.5 μm.
(5) The multilayer hard film-coated cutting tool according to (1) or (2), wherein the layer A has a layer thickness of 0.25 to 1.5 μm in the layer thickness constituting the lower layer.
(6) The multilayer hard film-coated cutting tool according to (1) or (2), wherein the B layer has a layer thickness of 0.25 to 2.5 μm in the layer thickness constituting the lower layer.
(7) At least one layer of the A layer and one layer of the B layer contain at least one component element selected from W, V, Mo, Nb, Ta, Hf, and Zr, or Si. The multilayer hard film-coated cutting tool according to any one of (1) to (6), which is further contained.
(8) In the B layer, there is a periodic composition change for at least one component of the component elements other than X, and the component indicates the maximum content rate of the periodic length (nm) of the periodic composition change. The period length is 20 to 200 nm when determined as the thickness of the position and the position indicating the maximum content adjacent to the position, and the composition variation rate of the periodic composition change is the maximum content and the minimum content of the component. The multilayer hard film according to any one of (1) to (7), which is characterized in that the composition variation rate is 5 to 95% when the difference in rate is obtained as the rate (%) divided by the maximum content rate. Coating cutting tool.
(9) A lowermost layer is formed between the tool substrate and the lower layer, and the lowermost layer includes the A layer having a layer thickness of 0.05 to 1.5 μm and a layer having a thickness of 0.05 to 2.5 μm. The multilayer hard film-coated cutting tool according to any one of (1) to (8), which comprises the thick B layer. "
It is characterized by.

Next, the covering tool of the present invention will be described together with the drawings.

FIG. 1 shows a schematic vertical cross-sectional schematic diagram of the multilayer hard coating of the coating tool having the multilayer rigid coating of the present invention.
In the present invention, for example, a multilayer hard film is formed on the surface of a tool substrate made of a WC-based cemented carbide by, for example, a physical vapor deposition method using an arc ion plating (AIP) apparatus shown in FIG.
As the upper layer (hereinafter, simply referred to as “upper layer”) as the outermost layer of the multilayer hard film, as shown as (Ti _z Si _1-z ) X in FIG. 1, the composition formula: (Ti _z Si ₁ ). _-Z ) A compound layer containing at least Ti and Si represented by X is coated.
Here, 0.7 ≦ z ≦ 0.99 (where z is an atomic ratio) is satisfied, and X is N, C, B, CN, BN, CBN, NO, CO, BO, CNO, BNO. , CBNO is one of them.
Since the upper layer composed of the compound layer containing at least Ti and Si has improved oxidation resistance by containing the Si component, it maintains excellent high hardness even under high temperature conditions during cutting. However, when z, which represents the content ratio of Ti in the total amount of Ti and Si, is less than 0.7, the high-temperature toughness and high-temperature strength of the upper layer decrease, while when z exceeds 0.99, the Si component. The effect of improving the hardness due to the inclusion of the above can not be obtained.
Therefore, the z value is 0.7 ≦ z ≦ 0.99 (however, the atomic ratio). Desirably, 0.85 ≦ z ≦ 0.95 (however, atomic ratio). Further, according to a preferred embodiment of the cutting test of the present invention, the upper layer is formed directly on the lower layer.
Further, the upper layer exhibits excellent wear resistance, but the component X represented by the composition formula: (Tiz Si _{1-z )} X is N, C, B, CN, BN, CBN, NO, Any of CO, BO, CNO, BNO, and CBNO is hard and exhibits similar characteristics.
Therefore, as the component X, any one selected from N, C, B, CN, BN, CBN, NO, CO, BO, CNO, BNO, and CBNO may be used. In order to meet the demands for better hardness and wear resistance, N or CN is suitable as the component X.
The action of the component X is the same in the A layer and the B layer described later as in the case of the upper layer.
When the thickness of the upper layer is 0.075 μm, excellent wear resistance cannot be exhibited over a long period of use, so that the tool life is short. On the other hand, when the thickness exceeds 1.5 μm, the upper layer is contained in the layer. Due to the internal stress, abnormal damage such as chipping, chipping, and self-destruction during cutting is likely to occur.
Therefore, the layer thickness of the upper layer is 0.075 to 1.5 μm. The layer thickness of the upper layer is more preferably 0.2 to 1.5 μm, and more preferably 0.6 to 1.5 μm.

As shown in FIG. 1, in the present invention, a lower layer is formed between the upper layer and the tool substrate.
Further, according to a preferred embodiment of the cutting test of the present invention, the upper layer is formed directly on the lower layer.
The lower layer is composed of a multi-layered film of A layer and B layer, and the layer thickness of the B layer is the same as or thicker than the layer thickness of the A layer, and the ratio of the thickness is the A layer: the B layer. = 1: 1 to 1: 2, and when the combination of one A layer and one B layer is a pair of layers, a multi-layered film having a repeating logarithm in the range of 2 pairs to 8 pairs. Consists of. Desirably, the layer thickness of the A layer layer is 0.25 to 1.5 μm, and the layer thickness of the B layer layer is 0.25 to 2.5 μm.
Here, the layer A is a compound layer containing at least Al and Cr represented by the composition formula: (Al _y Cr _1-y ) X. Further, according to the preferred embodiment of the cutting test of the present invention, the layer A is basically made of (Al _y Cr _1-y ) X.
Further, the B layer is composed of a compound (same as the A layer) containing at least Al and Cr represented by (Al _y Cr _1-y ) X and a composition formula: (Tiz Si _{1-z )} X (the above). It is a mixed layer of at least Ti and a compound containing Si (indicated by "(TiAlCrSi) X" in FIG. 1) represented by the same composition formula as the upper layer).
According to a preferred embodiment of the present invention, the mixed layer is composed of a (Ti _z Si _1-z ) X layer and an (Al _y Cr _1-y ) X layer, and the composition of the mixed layer is an individual (Ti). _z Si _1-z ) X layers and individual (Al _y Cr _1-y ) X layers are alternately laminated, and individual (Ti _z Si _1-z ) X constituting the mixed layer. Since the film thickness of each of the layer and the individual (Al _y Cr _1-y ) X layer is preferably nanometer size, it is preferable that the individual film thickness constituting the mixed layer does not exceed 100 nm. However, according to the present invention, since the mixed layer is formed by a simultaneous vapor deposition method, one (Ti _z Si _1-z ) X layer and one (Al _y Cr _1-y ) alternately laminated are formed. ) A mixed nanolayer composed of Al, Cr, Ti and X can be formed between the X layers.

The Al component, which is a constituent of the A layer, has the effect of improving high-temperature hardness, and the Cr component has the effect of improving high-temperature toughness and high-temperature strength, as well as improving oxidation resistance in the state where Al and Cr coexist and are contained. If y (however, atomic ratio) indicating the content ratio of Al in the total amount of Al and Cr is less than 0.2, the high-temperature hardness of the A layer becomes insufficient, while y is 0. If it exceeds 7, the high temperature toughness and high temperature strength of the A layer will decrease, so y was set to 0.2 ≦ y ≦ 0.7 (however, atomic ratio).
Further, the reason why the desired single layer thickness of the A layer is set to 0.25 to 1.5 μm is that if the thickness is less than 0.25 μm, the effect of the B layer having a laminated structure is remarkably exhibited, resulting in minute defects. When the thickness exceeds 1.5 μm, the relatively fast scraping of the A layer is dominant in the use as a film for tools. The reason is that it is not possible to obtain a sufficient life.

The B layer is, so to speak, a mixed layer of a layer having the same components as the Ti and Si compounds constituting the upper layer and a layer having the same components as the Al and Cr compounds constituting the A layer, and is a mixed layer of Ti and Si. It has both the characteristics of the compound layer and the characteristics of the Al and Cr compound layers.
The desirable layer thickness of the B layer is 0.25 to 2.5 μm, but if the thickness is less than 0.25 μm, the effect of the A layer having a laminated structure is remarkably exhibited, which is fast. Abrasion becomes dominant in use as a film for tools, and the life of the film for tools cannot be obtained. On the other hand, when the thickness exceeds 1.5 μm, wear of minute defects in use as a film for tools The reason is that it is not possible to obtain a sufficient life.

The lower layer is configured as a multi-layered film of the A layer and the B layer, but when the combination of one A layer and one B layer is a pair of layers, it is within the range of 2 to 8 pairs. The lower layer is composed of a multi-layered film consisting of a repeating logarithm.
This is because, as will be clarified in the examples below, when the repeating logarithm of the multi-layered film is less than 2 pairs or more than 8 pairs, the tool life in high-speed cutting is shortened.

At least one of the A layers and one of the B layers are further added with at least one component element selected from W, V, Mo, Nb, Ta, Hf, and Zr, or Si. Can be contained as.
Further, at least one layer and the B layer of the A layer contain at least one component element selected from W, V, Mo, Nb, Ta, Hf, and Zr, or Si in a total amount of 0.5. By containing it as an additional component of ~ 25 atomic%, the content of the additional component in the B layer can be adjusted.
In this case, the content of the additional component is 0.5 to 25 atomic%, for example, the ratio contained by substituting a part of the Cr content.
By containing the additional component in the A layer and the B layer, the wear resistance of the multilayer hard film is improved, the wear on the flank surface is suppressed, and the lubricity is improved, and as a result, the chip discharge property is improved. A multi-layer hard film containing such an additional component is suitable as, for example, a multi-layer hard film for a drill.

In the film formation of the B layer, the periodic composition of the component elements other than X is changed inside the B layer by simultaneous vapor deposition using an Al—Cr alloy target having a predetermined composition and a Ti—Si alloy target having a predetermined composition. Can be formed.
By forming such a periodic composition change, the hardness of the B layer can be increased, and at the same time, the stress relaxation effect in the layer can be obtained, so that cracks are generated and propagated due to the load during cutting. It is possible to exhibit remarkably excellent chipping resistance, chipping resistance and wear resistance as shown in Examples described later.

FIG. 2A shows a cross-sectional SEM image of a multilayer hard film on which a layer B having a periodic composition change is formed, FIG. 2B shows a partially enlarged view of layers A and B, and FIG. 2C shows a partially enlarged view. The schematic diagram of the B layer is shown.
FIG. 2A shows a lower layer composed of three pairs of A layer and B layer, and a multilayer hard film having an upper layer formed on the lower layer.
In the partially enlarged view shown in FIG. 2B, the layer thickness of one layer A is 0.25 μm, and the layer thickness of one layer B is 0.38 μm.
FIG. 2 (c) shows a schematic diagram of the layer B shown in FIG. 2 (b).
In addition, in FIGS. 2 (a) to 2 (c), N is contained as the component X.
The B layer shown in FIG. 2 (c) is a mixed layer of (Tiz Si _{1-z )} X and the above (Al _y Cr _1-y ) X. In FIG. 2 (c), the B layer has a component composition. Is not a uniform layer over the entire B layer, but a region having a high composition ratio of Ti and Si and a region having a high composition ratio of Al and Cr are formed as a striped pattern in the B layer, respectively.
When the composition of the B layer on which the striped pattern is formed is analyzed along the layer thickness direction using TEM-EDS, at least one component constituting the B layer is contained in the B layer having a layer thickness of 0.38 μm. Periodic composition change of the element, for example, the periodic composition change of the Ti component is formed, and the thickness of the position showing the maximum content of the Ti component and the position showing the maximum content adjacent to it is the period of the periodic composition change. When set to length, the period length is about 100 nm, and the composition fluctuation rate η = (C ₁ -C ₂ ) × 100 / C ₁ of the periodic composition change is in the range of 5 to 95%. I understand.
Here, C ₁ is the maximum content in the periodic composition change of the Ti component, C ₂ is the minimum content in the periodic composition change of the Ti component, and the difference between C ₁ and C ₂ is divided by C ₁ . The ratio (%) is defined as the composition fluctuation rate η.
The periodic composition change also changes the mechanical properties such as hardness and elastic modulus, and the appropriate range for the periodic length is in the range of 20 nm to 200 nm. If the period length is less than 20 nm, not only is it difficult to give composition fluctuations, but also the modulation of mechanical properties associated therewith becomes small, and the effect of extending the life of the tool cannot be greatly brought out. Further, when the cycle length exceeds 200 nm, not only the length of the composition fluctuation becomes large, but also the length of the change in the mechanical characteristics becomes large, and the effect of extending the life of the tool cannot be greatly brought out.

In the present invention, by forming the above-mentioned multilayer hard film on the surface of the tool substrate, both normal (low speed) cutting and high speed cutting do not cause chipping, chipping, etc., and over a long period of use. Although it exhibits excellent wear resistance, a bottom layer can be formed between the tool substrate and the multilayer hard film in order to increase the adhesion strength between the tool substrate and the multilayer hard film.
The lowermost layer is formed, for example, as a laminate of the A layer having a layer thickness of 0.05 to 1.5 μm and the B layer having a layer thickness of 0.05 to 2.5 μm, as shown in FIG. be able to.

Film formation method:
As shown in FIG. 3, for example, the film formation of the multilayer hard film of the coating tool of the present invention is performed by a physical vapor deposition method using an AIP device in which a plurality of types of cathode electrodes (evaporation sources) are provided in the device. Can be done.
(1) As shown in FIG. 3, a rotary table that revolves is provided in the AIP device, and a WC-based superhard alloy or the like is provided along the outer peripheral portion at a position radially separated from the central axis of the rotary table by a predetermined distance. A tool substrate is mounted so as to be rotatable, and a plurality of cathode electrodes (evaporation sources) are arranged across the rotary table.
For example, four electrodes made of an Al—Cr alloy having a predetermined composition and two electrodes made of a Ti—Si alloy having a predetermined composition are arranged in the AIP device so as to have the positional relationship shown in FIG.
(2) Film formation of the bottom layer:
In order to form a film of the lowermost layer of the covering tool of the present invention by the AIP device, for example, a predetermined reaction gas is introduced into the device, and an arc discharge is generated only between the Al—Cr alloy having a predetermined composition and the anode electrode. First, a lower layer A having a predetermined thickness is formed on the surface of the tool substrate.
Then, an arc discharge is generated between the Al—Cr alloy having a predetermined composition and the anode electrode, and at the same time, an arc discharge is generated between the Ti—Si alloy having the predetermined composition and the anode electrode. A layer B having a predetermined layer thickness (that is, a mixed layer of (Aly Cr _{1-y )} X and (Ti _z Si _1-z ) X) is formed on the surface of the formed layer A.
(3) Formation of lower layer:
Then, in order to form the A layer of the lower layer, a predetermined reaction gas is introduced into the apparatus, and an arc discharge is generated only between the Al—Cr alloy having a predetermined composition and the anode electrode to form the lowermost layer. A layer having a predetermined thickness is formed on the surface.
Further, in order to form the B layer of the lower layer, a predetermined reaction gas is introduced into the apparatus to generate an arc discharge between the Al—Cr alloy having a predetermined composition and the anode electrode, and at the same time, Ti— having a predetermined composition. By simultaneous vapor deposition (codepo) that generates an arc discharge between the Si alloy and the anode electrode, the B layer (that is, (Al _y Cr _{1-y )} X and (Tiz) having a predetermined layer thickness is formed on the surface of the A layer formed above. A mixed layer with Si _1-z ) X. In FIG. 1, "(TiAlCrSi) X") is formed.
The film formation of the lower layer can be formed by alternately repeating the film formation of the A layer and the B layer of the lower layer until a predetermined layer thickness is reached.
When forming the B layer of the lowermost layer and the B layer of the lower layer, regarding the periodic length of the periodic composition change and the composition fluctuation rate, the rotation speed of the rotary table is adjusted, and a plurality of cathode electrodes in the AIP device. It can be controlled by adjusting the number and position of installations, ON-OFF timing of arc discharge, and the like.
(4) Upper layer film formation:
For the film formation of the upper layer, an upper layer having a predetermined thickness is formed on the surface of the lower layer by introducing a predetermined reaction gas into the apparatus and generating an arc discharge only between the Ti—Si alloy having a predetermined composition and the anode electrode. A film can be formed.
When forming the lowermost layer, the lower layer, and the upper layer, it is necessary to select the type of the reaction gas according to the type of the X component, but N, C, B, and O are included as the X component. In this case, for example, a reaction gas containing N ₂ , CH ₄ , C ₃ H ₉ B, O ₂ , or the like may be used as the reaction gas component, respectively.
Further, when the multilayer hard film further contains at least one component element selected from W, V, Mo, Nb, Ta, Hf, and Zr, or Si, for example, a layer A is formed. As the cathode electrode, an alloy in which the above-mentioned component element is further contained in an Al—Cr alloy may be used.

In the present invention, the upper layer of the covering tool coated with the multilayer hard film is the (Ti _z Si _1-z ) X layer having a layer thickness of 0.075 to 1.5 μm (where z is 0.7 ≦ in atomic ratio). It is composed of z ≦ 0.99), and the lower layer of the multilayer hard film is formed from (Al _y Cr _1-y ) X layer (where y is an atomic ratio, 0.2 ≦ y ≦ 0.7). A layer and a B layer composed of a mixed layer of the (Tiz Si _{1-z )} X and the (Al _y Cr _1-y ) X are alternately laminated, and the layer thickness of the B layer at that time is It is the same as or thicker than the layer thickness of the A layer, and the ratio of the thickness is assumed to be A layer: B layer = 1: 1 to 1: 2, and one with one A layer in the lower layer. When the combination of two B layers is one pair, the lower layer is composed of a multi-layered film having repeating pairs in the range of 2 to 8 pairs, whereby the covering tool of the present invention has normal (low speed) cutting conditions. It exhibits excellent wear resistance without causing abnormal damage such as chipping and chipping under any of the high-speed cutting conditions, and further, even if the upper layer is thickened, abnormal damage such as chipping and chipping occurs. Since there is no fear, it is possible to obtain a covering tool having excellent cutting performance over a long period of use and having versatility.
Further, when the periodic composition change is formed in the B layer with a predetermined periodic length and a predetermined composition fluctuation rate, the chipping resistance, the chipping resistance, and the wear resistance are further improved, and the covering tool can be used. The life is extended.

A schematic vertical cross-sectional view of the multilayer hard coating of the coating tool having the multilayer hard coating of the present invention is shown. As an example of the covering tool of the present invention, (a) shows a cross-sectional SEM image of a multilayer hard film having a B layer having a periodic composition change, and (b) shows a partially enlarged view of the A layer and the B layer. It is shown, and the schematic diagram of the B layer is shown in (c). The AIP apparatus used for forming a multilayer hard film on a drill surface is shown, (a) is a schematic plan view, and (b) is a schematic front view. (A) to (j) are photographs observing the wear state of the cutting edge of each drill in the middle stage of the cutting test under the cutting condition A (high-speed cutting) (when the cutting length reaches 57.0 m). be. (A) to (j) are photographs of observing the wear state of the cutting edge of each drill that has reached the end of its life in the cutting test under the cutting condition A (high-speed cutting). In (a) to (j), the wear state of the cutting edge of each drill is observed in the middle stage of the cutting test under the cutting condition B (normal (low speed) cutting) (when the cutting length reaches 66.5 m). It is a photograph that was taken. (A) to (j) are photographs of observing the wear state of the cutting edge of each drill that has reached the end of its life in the cutting test under the cutting condition B (normal (low speed) cutting). It is a graph which shows the relationship between the repeating logarithm (pair) of A layer and B layer in the lower layer of a multilayer hard film, and the life of a drill. It is a graph which shows the relationship between the layer thickness of the upper layer of a multilayer hard film, a cutting length or a life ratio 1, (a) shows the case of high-speed cutting, and (b) shows the case of normal (low-speed) cutting. ..

Next, the covering tool of the present invention will be specifically described with reference to Examples.
In the following examples, a drill coated with a multi-layer hard film will be described, but an insert attached to the tip of a cutting tool for turning or planing, or surface milling, grooving, or shoulder machining of a work material. The present invention is also applied to covering tools such as solid type end mills and insert type end mills used for such purposes.

First, a raw material powder containing WC powder, Co powder, etc. is blended into a predetermined compounding composition, wet-mixed with a ball mill, dried, and then press-molded into a green compact at a pressure of 100 MPa, and the green compact is 6Pa. Sintered in vacuum at a temperature of 1400 ° C. for 1 hour to form a round bar sintered body made of WC-based cemented carbide with a diameter of 13 mm, and further ground from this round bar sintered body. In processing, a WC-based cemented carbide drill substrate (hereinafter referred to as "drill substrate") having a two-blade shape with a groove forming portion diameter x length of 8 mm x 22 mm and a twist angle of 30 degrees, respectively. ) Was produced.
The composition of the drill substrate produced here is 90% by mass of tungsten carbide (WC) and 10% by mass of cobalt (Co).
The cutting edges of these drill substrates were then honed, ultrasonically cleaned in acetone and dried.

The drill substrate produced above was charged into the AIP apparatus shown in FIG. 3 to form a multilayer hard film shown in Table 1.
specifically,
(A) The drill substrate is mounted along the outer peripheral portion at a position radially separated from the central axis on the rotary table in the AIP device shown in FIG. 3 by a predetermined distance, and the rotary table is mounted in the AIP device. Four cathode electrodes (evaporation sources) made of an Al—Cr alloy having a predetermined composition and two cathode electrodes (evaporation sources) made of a Ti—Si alloy having a predetermined composition were arranged sandwiched between them.
(B) First, the inside of the device is evacuated and kept in a vacuum of 0.1 Pa or less, the inside of the device is heated to 500 ° C. with a heater, and then the device rotates on a rotary table rotating at a rotation speed of 0.5 to 5 rpm. A DC bias voltage of −1000 V was applied to the rotating tool substrate, and a current of 100 A was passed between the Al—Cr alloy and the anode electrode to generate an arc discharge, whereby the surface of the drill substrate was bombarded.
(C) Next, the atmosphere inside the apparatus is maintained in a nitrogen atmosphere of 0.5 to 9.0 Pa, and a DC bias voltage of -20 to -150 V is applied to the tool substrate that rotates while rotating on the rotary table, and Al is applied. An arc discharge was generated by passing a current of 120 A between the Cr alloy electrode and the anode electrode to deposit and form an (Al _y Cr _1-y ) N layer having the target composition and target layer thickness shown in Table 1. ..
(D) Then, while continuing the arc discharge between the Al—Cr alloy electrode and the anode electrode, a current of 120 A is passed between the Ti—Si alloy electrode and the anode electrode to generate an arc discharge. A mixed layer of the target layer thickness is formed by simultaneous deposition of the (Al _y Cr _1-y ) N layer and the (Tiz Si _{1-z )} N layer, and the bottom is formed by the film formation of (c) and (d). A layer was formed.
(E) Next, the atmosphere inside the apparatus is maintained in a nitrogen atmosphere of 0.5 to 9.0 Pa, and a DC bias voltage of -20 to -150 V is applied to the drill substrate that rotates while rotating on the rotary table, and Al- An arc discharge was generated by passing a current of 120 A between the Cr alloy electrode and the anode electrode to form an A layer having a target composition and a target layer thickness shown in Table 1.
(F) Then, while maintaining the atmosphere inside the apparatus in a nitrogen atmosphere of 0.5 to 9.0 Pa, a DC bias voltage of -20 to -150 V is applied to the tool substrate that rotates while rotating on the rotary table, and , A current of 120 A is passed between the Al—Cr alloy and the anode electrode to continue the arc discharge, and a current of 120 A is passed between the Ti—Si alloy electrode and the anode electrode to generate an arc discharge. , (Al _y Cr _1-y ) N layer and (Ti _z Si _1-z ) N layer were simultaneously vapor-deposited to form a mixed layer (B layer) having a target layer thickness shown in Table 1.
(G) A table having a repeating logarithm in the range of 1 to 20 pairs when one A layer and one B layer are made into a pair by repeating the steps (e) and (f). A lower layer having the target layer thickness shown in 1 was formed.
(H) Next, the atmosphere inside the apparatus is maintained in a nitrogen atmosphere of 0.5 to 9.0 Pa, and a DC bias voltage of -20 to -150 V is applied to the drill substrate that rotates while rotating on the rotary table, and Ti- An arc discharge was generated by passing a current of 120 A between the Si alloy electrode and the anode electrode to form an upper layer having a target composition and a target layer thickness shown in Table 1.
By performing the steps (a) to (h) and forming a multilayer hard film having a predetermined layer thickness by vapor deposition as shown in Table 1, test specimen drills 1 to 8 as a multilayer hard film covering tool were manufactured, respectively.
The component X of the hard film in the test piece drills 1 to 8 produced above is N (nitrogen).

Further, in order to evaluate the characteristics of the test piece drills 1 to 8 manufactured above, the covering tool proposed in Patent Document 3 is manufactured by using an AIP device, and this is used as a conventional drill 1 for evaluation criteria. bottom.
In the production of the conventional drill 1, the inside of the AIP device was set to a nitrogen gas atmosphere, and an Al—Ti alloy electrode and an Al—Cr alloy electrode were used as cathode electrodes to deposit and form a multilayer hard film shown in Table 2.

Further, the covering tool proposed in Patent Document 2 was manufactured by using an AIP device, and this was used as a conventional drill 2 for evaluation criteria.
In the production of the conventional drill 2, the inside of the AIP device was set to a nitrogen gas atmosphere, and a Ti electrode and a Ti—Al alloy electrode were used as cathode electrodes to deposit and form a multilayer hard film shown in Table 2.

For the test specimen drills 1 to 8 produced above, the conventional drill 1, and the conventional drill 2, the layer thickness of each of the multilayer hard coatings is directly measured by SEM by ion-etching the cutting edge portion, and the component composition is measured. Multiple points of TEM-EDS are measured for each film thickness, and the average value is used to determine the period length of the periodic composition change. Obtained as the interval between the thickness of the position showing the maximum content and the position showing the maximum content adjacent to it, and the composition variation rate is the ratio obtained by dividing the difference between the maximum content and the minimum content of each component by the maximum content. I decided.
The cycle length and composition volatility were calculated from the measured values of the Ti component.
Tables 1 and 2 show these results.

Then, the test piece drills 1 to 8 and the conventional drills 1 and 2 were subjected to a cutting test under the following cutting conditions A.
Cutting condition A (high-speed cutting):
Work Material-Plane Dimension: 100 mm x 250 mm, Thickness: 25 mm JIS S50C Plate Cutting Speed: 200 m / min. ,
Feed: 0.35 mm / rev. ,
Hole depth: 25 mm,
Coolant: Water-soluble cutting oil, 1 MPa,
Wet high-speed drilling and cutting test of carbon steel under the conditions of
Was done.
When the cutting length in the middle of the cutting test reached 57.0 m, the cutting test was interrupted for each drill and the wear state of the cutting edge was observed.
FIG. 4 shows the observation results.
Then, the cutting test was continuously carried out, and the time when the flank wear width of the cutting edge exceeded 0.3 mm was defined as the life, and the cutting length up to the life was determined.
The location where the flank wear width was measured was set to a position facing the center of the drill by 0.5 mm from the outermost circumference of each drill.
Table 3 shows the test results.
In addition, the wear state of the cutting edge of the drill that reached the end of its life was observed for the test piece drills 1 to 8 and the conventional drills 1 and 2.
FIG. 5 shows the observation results.
According to FIG. 4, as can be seen from the photograph of part A, the flank wear width of the conventional drill 1 is significantly larger than that of the drills 2 to 4, and the flank wear width of the conventional drill 2 is the same. As can be seen from the photograph of part B, the wear of the margin is remarkable, though it is a degree.
As a result, as shown in FIG. 5, the conventional drill 1 is damaged due to the weakening of the cutting edge due to the progress of wear on the flank, and the conventional drill 2 is also damaged due to the increase in cutting resistance due to the progress of margin wear. It has a shorter life than 4 (corresponding to the drill of the present invention).
Further, the comparison between the test body drills 2 to 4 (drill of the present invention) and the test body drills 1, 5 to 8 (comparative example) will be described. First, regarding the change in the cutting length of the flank wear width, there is no big difference between the test piece drills 2 to 4 and the test body drills 1, 5 to 8.
Further, as shown in FIG. 5, the life of the test piece drills 1, 5 to 8 is the same as or slightly longer than that of the conventional drill. However, due to the influence of residual stress in the coating at the initial stage of cutting, chipping of 0 commas and several millimeters occurs in multiple places near the cutting edge in any of the test piece drills 1, 5 to 8, and the quality of the machined hole is poor. , Inferior to specimen drills 2-4. The reason why it is affected by the residual stress in the film is that the number of interfaces is large due to the large number of repeating logarithms between the A layer and the B layer, and especially for the test piece drills 7 and 8, the number of interfaces is large and further. The thickness of TiSiN in the upper layer is relatively thick.

Further, the test piece drills 1 to 8 and the conventional drills 1 and 2 were subjected to a cutting test under the following cutting condition B.
Cutting condition B (normal (low speed) cutting):
Work Material-Plane Dimension: 100 mm x 250 mm, Thickness: 25 mm JIS S50C Plate Cutting Speed: 120 m / min. ,
Feed: 0.25 mm / rev. ,
Hole depth: 25 mm,
Coolant: Water-soluble cutting oil, 1 MPa,
Wet drilling and cutting test of carbon steel under the conditions of
Was done.
When the cutting length in the middle of the cutting test reached 66.5 m, the cutting test was interrupted for each drill and the wear state of the cutting edge was observed.
FIG. 6 shows the observation results.
Then, the cutting test was continuously carried out, and the time when the flank wear width of the cutting edge exceeded 0.3 mm was defined as the life, and the cutting length up to the life was determined.
The location where the flank wear width was measured was set to a position facing the center of the drill by 0.5 mm from the outermost circumference of each drill.
Table 4 shows the test results.
In addition, the wear state of the cutting edge of the drill that reached the end of its life was observed for the test piece drills 1 to 8 and the conventional drills 1 and 2.
FIG. 7 shows the observation results. Some of the specimen drills 1, 5 to 8 have a considerably longer life than the conventional drills. However, as in the test of cutting condition A, due to the influence of residual stress in the film at the initial stage of cutting, chipping of 0 comma several millimeters occurs in the vicinity of the cutting edge in any of the test piece drills 1, 5 to 8. The quality of the machined hole is poor, and it is inferior to the test piece drills 2-4. The reason why it is affected by the residual stress in the film is that the number of interfaces is large due to the large number of repeating logarithms between the A layer and the B layer, and especially for the test piece drills 7 and 8, the number of interfaces is large and further. The thickness of TiSiN in the upper layer is relatively thick, which is the same as the cutting condition A.

Next, the relationship between the repeating logarithm of the A layer and the B layer in the lower layer and the tool life was investigated.
Repeating layers A and B mainly in the lower layer under the condition that the layer thickness of the upper layer is kept constant at 0.2 μm and the layer structure, component composition of the lowermost layer and the component composition of the lower layer are made as similar as possible. A plurality of test piece drills having different logarithmic values shall be prepared, and these test piece drills shall be subjected to a high-speed cutting test at a cutting speed of 200 m / min (same as the above-mentioned cutting test of carbon steel under the cutting condition A). From the test results obtained by, the life ratio 1 of each drill was determined.
FIG. 8 shows the test results (life ratio 1). The values for the test piece drill with 1, 5, 10 and 20 pairs of repeating logarithms were plotted in the figure.
From FIG. 8, it can be seen that the lifetime ratio of 1 is 160% or more in the range where the repeating logarithm of the A layer and the B layer in the lower layer is 2 to 8 pairs.
This is the reason why the repeating logarithm of the A layer and the B layer in the lower layer is defined as 2 to 8 pairs in the present invention.

In addition, the relationship between the thickness of the upper layer and the life ratio 1 was investigated.
Under the condition that the composition and layer structure of the lowermost layer and the lower layer were the same, a plurality of test specimen drills in which the layer thickness of the upper layer was changed within the range of 0.075 μm to 1.5 μm were prepared. High-speed cutting test with a cutting speed of 200 m / min (same as the cutting test for carbon steel under the above-mentioned cutting condition A) and normal (low-speed) cutting test with a cutting speed of 120 m / min (the above-mentioned cutting condition B). The cutting length and life ratio 1 were determined by subjecting the carbon steel to the same cutting test).
FIG. 9 (a) shows the test results (cutting length, life ratio 1) by the high-speed cutting test, and FIG. 9 (b) shows the test results (cutting length, life ratio 1) by the normal (low speed) cutting test. show. The test results (cutting length, life ratio) when the layer thickness of the upper layer was 0.05 μm, 0.1 μm, 0.3 μm, 0.5 μm, 0.6 μm, 1 μm, 1.25 μm and 1.75 μm. 1) was plotted in the figure.
According to FIG. 9A, in the case of high-speed cutting, the life ratio 1 exceeds 100% when the layer thickness of the upper layer is 0.075 μm or more, and the life ratio 1 is almost 200 when the layer thickness is 0.6 μm or more. Although it saturates between about 250%, according to FIG. 9B, it can be seen that in the case of normal (low speed) cutting, the life ratio 1 increases in proportion to the layer thickness of the upper layer.
In any case, when the layer thickness of the upper layer is 0.075 μm or more and 1.5 μm or less, preferably 0.2 μm or more and 1.0 μm or less, it is either high-speed cutting or normal (low-speed) cutting. However, since the cutting length is large and the life ratio is 1 high, it can be seen that excellent cutting performance is exhibited for a long period of time without causing abnormal damage such as chipping and chipping.

From the results of Example 1 shown in Tables 3 and 4, the multilayer hard film-coated cutting tool (test piece drills 2, 3, and 4) of the present invention that satisfies the requirements specified in the present invention is predetermined as the upper layer. It is composed of a compound layer containing at least Ti and Si having a composition and a predetermined layer thickness, and the lower layer is composed of a multi-layered film composed of 2 to 8 pairs of repeating pairs of A layer and B layer, and The layer A is formed as a compound layer containing at least Al and Cr, and the layer B is formed as a mixed layer of the compound containing at least Ti and Si and the layer A, whereby high-speed cutting and normal (low speed) can be performed. It is versatile for both cutting, and compared to the conventional drill 1 and the conventional drill 2, it can exhibit excellent cutting performance for a long period of time without causing abnormal damage such as chipping and chipping. Understand.

The film forming steps (a) to (h) in Example 1 were performed on a drill substrate having a component composition of 90% by mass of tungsten carbide (WC) and 10% by mass of cobalt (Co), and the predetermined values shown in Table 5 were performed. Specimen drills 9 to 38 as a multi-layer hard film covering tool were manufactured by vapor-filming and forming a multi-layer hard film having the same layer thickness.
However, in the film formation of the test piece drill 15, the atmosphere inside the apparatus was set to a mixed gas atmosphere of N ₂ and CH ₄ , and the component X of the hard film was CN (nitrogen carbide).
Further, when forming the film of the test piece drills 16 to 18, by using an electrode containing Zr, Nb, and W as the Al—Cr alloy electrode, Zr is formed in the B layer in the film of the test piece drills 16 to 18, respectively. , Nb, W are contained in 1 atomic%.

For the test body drills 9 to 38 produced above, the layer thickness, the component composition, the periodic length of the periodic composition change, and the composition fluctuation rate of each of the multilayer hard coatings were determined in the same manner as in Example 1.
Table 5 shows the results.

The test piece drills 9 to 38 produced above were subjected to a cutting test under the same cutting conditions as in Example 1 (that is, cutting condition A (high-speed cutting) and cutting condition B (normal (low-speed) cutting)).
Further, the characteristics of the test piece drills 9 to 38 were evaluated by comparing the conventional drill 1 and the conventional drill 2 shown in Table 2 used in Example 1.
Tables 6 and 7 show the cutting test results.

According to the test results of the cutting condition A shown in Table 6, the hard film including the margin portion of the test piece drill 9 of the comparative example wears quickly, and the life ratio with the conventional drills 1 and 2 is 76% shorter. The test piece drill (Comparative Example) 11 of the comparative example had a crack in the film at an early stage of cutting, and the life ratio with the conventional drills 1 and 2 was as short as 76%. Further, the test piece drill (Comparative Example) 12 of the comparative example had a crack in the film at an early stage of cutting, and the life ratio with the conventional drills 1 and 2 was 58% shorter.
However, the multi-layer hard film-coated cutting tool (test piece drills 10, 13 to 18) of the present invention has a life ratio of more than 150% with that of the conventional drills 1 and 2.
For the test piece drills 19 to 22, the layer thickness of the upper layer is different, and for the test piece drill 19 having a layer thickness of less than 0.075 μm and the test piece drill 22 having a layer thickness of more than 1.5 μm. As a result, the life of each of the conventional drills is extremely shortened. For the test piece drill 19, the upper layer TiSiN is thin and cannot exert the effect of wear resistance, and for the test piece drill 22, the hard TiSiN of the upper layer is too thick, so that it is resistant to external force during cutting. The effect of extending the life was not obtained due to the occurrence of a defect. The life ratios of the test specimen drills 20 and 21 having an appropriate upper layer thickness to those of the conventional drills 1 and 2 exceed 150%, respectively.
Regarding the specimen drills 23 and 24, the thickness of the lower layer A is more than the thickness of the B layer, and the thickness of the B layer is more than twice the thickness of the A layer, respectively. For the reason described in [0017], the result was that the life ratio with the conventional drills 1 and 2 could not exceed 100%.
The test piece drill 25 has the Ti concentration of the upper layer increased to the limit, and is in a region where the wear resistance effect of TiSiN can no longer be obtained. The result was that the life ratio with 2 was less than 50%.
For the specimen drills 26 and 27, the periodic composition changes of the B layer, which is the mixed layer of the lower layer, are set to 12 nm and 250 nm, respectively, and the composition variation rate is large at 12 nm, which is less than 20 nm. It is not possible, and at 250 nm, where the period length exceeds 200 nm, changes in mechanical properties appear at intervals larger than the appropriate range, so the life ratio with the conventional drills 1 and 2 can exceed 100%. The result did not reach 200%.
For the specimen drills 28 to 31, the ratio of the layer thickness of the lower layer A and the layer B is within the range shown in paragraph [0015], and the layer thickness of the A layer is 0.15 μm, 1.75 μm, and the B layer, respectively. The layer thickness is 0.2 μm and 2.7 μm, and the life ratio with the conventional drills 1 and 2 is the same as that of the test specimen drills 23 and 24 for the reasons described in paragraphs [0016] and [0017]. Although it exceeded 150%, it did not reach 200%.
For the test piece drills 32 to 35, the layer thicknesses of the A layer and the B layer of the lowermost layer are changed. For the specimen drills 32 and 33, the layer thickness of the A layer was 0 μm and 1.5 μm, respectively, and for the specimen drills 34 and 35, the thickness of the B layer was 0 μm and 1.5 μm, respectively. Is. For the same reason as the test piece drills 23 and 24, the life extension effect is not remarkable in the life ratio with the conventional drills 1 and 2, and particularly in the test body drills 32 and 34 in which the layer thickness of the A layer and the B layer is 0 μm. The result was about 120% in terms of life ratio with drills 1 and 2.
For the specimen drills 36 to 38, the composition volatility of Ti in the lower B layer was 98.9%, 2.1%, and 71.5%, respectively, and the composition volatility exceeded 95%. For the test piece drill 36 and the test piece drill 37 having a composition volatility of less than 5%, the magnitude of the fluctuation of the mechanical characteristics due to the large composition fluctuation rate and the fluctuation of the mechanical characteristics due to the small composition volatility, respectively. Due to its small size, the life ratio with the conventional drills 1 and 2 exceeded 150%, but the result did not reach 200%. The life ratio with 2 was 197%.

Further, according to the cutting test of the cutting condition B shown in Table 7, the hard film of the test piece drill 9 of the comparative example wears quickly as in the cutting condition A, and the life ratio with the conventional drill 1 is 77%. The life ratio with the conventional drill 2 is 64% shorter, the test piece drill 11 of the comparative example has a crack in the film at an early stage of cutting, and the life ratio with the conventional drill 1 is 83%, which is with the conventional drill 2. The life ratio was as short as 68%. Further, the test piece drill 12 of the comparative example had a short life of 60% with the conventional drill 1 and 50% with the conventional drill 2 due to cracks in the film at an early stage of cutting.
However, the multilayer hard film-coated cutting tool (test piece drills 10, 13 to 18) of the present invention has a life ratio of 173% or more with the conventional drill 1 and a life ratio of 143% or more with the conventional drill 2. The result was.
A test piece obtained by forming a film using an electrode containing V, Mo, Ta, Hf, and Si as an Al—Cr alloy electrode and further containing V, Mo, Ta, Hf, and Si in the B layer. As for the drill, the same results as those of the test piece drills 16 to 18 are obtained in the cutting test under the cutting condition A (high-speed cutting) and the cutting condition B (normal (low-speed) cutting).
For the test piece drills 19 to 22, the layer thickness of the upper layer is different. For the test piece drill 19 having a layer thickness of less than 0.075 μm, the life ratio 1 is 58%, the life ratio 2 is 48%, and for the test piece drill 22 having a layer thickness exceeding 1.5 μm, the life ratio 1 is 53%. The life ratio of 2 is 44%, which results in an extremely short life compared to the conventional drill. For the test piece drill 19, the upper layer TiSiN is thin and cannot exert the effect of wear resistance, and for the test piece drill 22, the hard TiSiN of the upper layer is too thick, so that it is resistant to external force during cutting. The effect of extending the life was not obtained due to the occurrence of a defect. The life ratios of the test specimen drills 20 and 21 having an appropriate upper layer thickness to those of the conventional drills 1 and 2 exceed 150%, respectively.
Regarding the specimen drills 23 and 24, the thickness of the lower layer A is more than the thickness of the B layer, and the thickness of the B layer is more than twice the thickness of the A layer, respectively. For the reason described in [0017], the result was that the life ratio with the conventional drills 1 and 2 could not exceed 100%.
Regarding the test piece drill 25, the Ti concentration of the upper layer is increased to the limit, and it is a region where the wear resistance effect of TiSiN can no longer be obtained. As a result, the life ratio with the conventional drills 1 and 2 was less than 50%.
For the specimen drills 26 and 27, the periodic composition changes of the B layer, which is the mixed layer of the lower layer, are set to 12 nm and 250 nm, respectively, and the composition variation rate is large at 12 nm, which is less than 20 nm. It was not possible, and at 250 nm, where the period length exceeds 200 nm, changes in mechanical properties appear at intervals larger than the appropriate range, so the result was that the life ratio with the conventional drill 2 was slightly over 100%.
For the specimen drills 28 to 31, the ratio of the layer thickness of the lower layer A and the layer B is within the range shown in paragraph [0015], and the layer thickness of the A layer is 0.15 μm, 1.75 μm, and the B layer, respectively. The layer thickness is 0.2 μm and 2.7 μm, and the life ratio with the conventional drill 2 is 100% for the reason described in paragraphs [0016] and [0017] as in the case of the test specimen drills 23 and 24. The result was slightly higher than that.
For the test piece drills 32 to 35, the layer thicknesses of the A layer and the B layer of the lowermost layer are changed. For the specimen drills 32 and 33, the layer thickness of the A layer was 0 μm and 1.5 μm, respectively, and for the specimen drills 34 and 35, the thickness of the B layer was 0 μm and 1.5 μm, respectively. Is. For the same reason as the test piece drills 23 and 24, the life ratio with the conventional drill 2 was slightly over 100%.
For the specimen drills 36 to 38, the composition volatility of Ti in the lower B layer was 98.9%, 2.1%, and 71.5%, respectively, and the composition volatility exceeded 95%. For the test piece drill 36 and the test piece drill 37 having a composition volatility of less than 5%, the magnitude of the fluctuation of the mechanical characteristics due to the large composition fluctuation rate and the fluctuation of the mechanical characteristics due to the small composition volatility, respectively. Due to its small size, the life ratio with the conventional drills 1 and 2 was slightly over 100%, but for the test piece drill 38, which has an appropriate composition volatility, the life ratio with the conventional drills 1 and 2 is 150. The result exceeded%.

From the results of Example 1 shown in Tables 3 and 4, and further from the results of Example 2 shown in Tables 6 and 7, the multilayer hard film-coated cutting tool of the present invention has a predetermined composition and a predetermined composition as an upper layer. The layer thickness is composed of a compound layer containing at least Ti and Si, and the lower layer is composed of a multi-layered film composed of 2 to 8 pairs of repeating pairs of A layer and B layer, and the A layer is composed of a multi-layered film. The compound layer containing at least Al and Cr, and the B layer are configured as a mixed layer of the compound containing at least Ti and Si and the A layer, so that either high-speed cutting or normal (low-speed) cutting can be performed. Moreover, it exhibits excellent cutting performance for a long period of time without causing abnormal damage such as chipping and chipping as compared with the conventional drill 1 and the conventional drill 2.

The multi-layer hard film-coated cutting tool of the present invention has versatility and excellent cutting characteristics, so that metal materials such as carbon steel and alloy steel, which are widely used in the automobile industry, can be used with high efficiency and long life. Can be machined with.

Claims (9)

In a multi-layer hard film-coated cutting tool including the tool substrate in which a multi-layer hard film is formed on the surface of the tool substrate.
(A) The multilayer hard film includes at least an upper layer as the outermost layer of the multilayer hard film and a lower layer provided between the outermost layer of the multilayer hard film and the surface of the tool substrate .
(B) The upper layer as the outermost layer of the multilayer hard film is composed of a compound layer of Ti, Si and X having a layer thickness of 0.075 to 1.5 μm containing Ti and Si, and the Ti, A compound of Si and X,
Composition formula: (Tiz Si _{1-z )} X
When represented by, 0.7 ≦ z ≦ 0.99 (where z is an atomic ratio) is satisfied, and X is N, C, B, CN, BN, CBN, NO, CO, BO, CNO. , BNO, CBNO, which is one of the following
(C) The lower layer is composed of a multi-layered film of A layer and B layer, and the layer thickness of the B layer is the same as or thicker than the layer thickness of the A layer, and the ratio of the thickness is A. Layer: B layer = 1: 1 to 1: 2, and when the combination of one A layer and one B layer is a pair of layers, the repeating logarithm within the range of 2 pairs to 8 pairs is set. It consists of a multi-layered film that has
(D) The layer A is a compound layer of Al, Cr and X containing at least Al and Cr, and the compound of Al, Cr and X is used.
Composition formula: (Al _y Cr _1-y ) X
When represented by, 0.2 ≦ y ≦ 0.7 (where y is an atomic ratio) is satisfied, and X is N, C, B, CN, BN, CBN, NO, CO, BO, CNO. , BNO, CBNO, which is one of the following
(E) The B layer is a mixed layer of the (Ti _z Si _1-z ) X and the (Al _y Cr _1-y ) X, and the X is N, C, B, CN, BN, CBN. , NO, CO, BO, CNO, BNO, CBNO, a multi-layer hard film coating cutting tool. The mixed layer is composed of a (Ti _z Si _1-z ) X layer and a (Al _y Cr _1-y ) X layer, and the composition of the mixed layer is an individual (Ti _z Si _1-z ) X layer and an individual. (Al _y Cr _1-y ) X layers are alternately laminated, and individual (Ti _z Si _1-z ) X layers and individual (Al _y Cr _1- ) constituting the mixed layer are laminated. _y ) The multilayer hard film-coated cutting tool according to claim 1, wherein the thickness of each of the X layers does not exceed 100 nm. The multilayer hard film-coated cutting tool according to claim 1 or 2, wherein the upper layer containing at least Ti and Si has a layer thickness of 0.2 to 1.5 μm. The multilayer hard film-coated cutting tool according to claim 1 or 2, wherein the upper layer containing at least Ti and Si has a layer thickness of 0.6 to 1.5 μm. The multilayer hard film-coated cutting tool according to claim 1 or 2, wherein the layer A has a layer thickness of 0.25 to 1.5 μm in the layer thickness constituting the lower layer. The multilayer hard film-coated cutting tool according to claim 1 or 2, wherein the B layer has a layer thickness of 0.25 to 2.5 μm constituting the lower layer. At least one layer of the A layer and one layer of the B layer further contain at least one component element selected from W, V, Mo, Nb, Ta, Hf, and Zr, or Si. The multilayer hard film-coated cutting tool according to any one of claims 1 to 6, wherein the tool is used. In the B layer, there is a periodic composition change for at least one component of the component elements other than X, and the periodic length (nm) of the periodic composition change is set at the position where the component shows the maximum content and the position thereof. The period length is 20 to 200 nm when determined as the thickness of the position indicating the adjacent maximum content, and the composition variation rate of the periodic composition change is the difference between the maximum content and the minimum content of the component. The multilayer hard film-coated cutting tool according to any one of claims 1 to 7, wherein the composition variation rate is 5 to 95% when determined as a ratio (%) obtained by dividing .. A lowermost layer is formed between the tool substrate and the lower layer, and the lowermost layer is the A layer having a layer thickness of 0.05 to 1.5 μm and the A layer having a layer thickness of 0.05 to 2.5 μm. The multilayer hard film-coated cutting tool according to any one of claims 1 to 8, which comprises a B layer.

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